System and method for fabricating and curing large composite structures

ABSTRACT

A system and method for fabricating large composite fuselages or other vehicle structures, in which the composite structure is fabricated and cured as on a tool, segmented and removed from the tool without disassembling the tool, and then reassembled off the tool to reform the large structure. The tool includes mandrel segments attached to a substructure. The attachments may be moveable to accommodate differential expansion and contraction during curing, and the tool may be rotatable to facilitate access. A composite material of resin and synthetic fibers is applied over the mandrel segments to fabricate the structure on the tool. Caul plates are secured over the composite material, and the composite material is cured on the tool. The resulting structure is cut into part segments which are then removed from the tool, and the part segments are joined to reassemble the large composite structure off the tool.

RELATED APPLICATION

The present U.S. non-provisional patent application is acontinuation-in-part and claims priority benefit of a prior-filed U.S.non-provisional patent application having the same title, Ser. No.16/525,772, filed Jul. 30, 2019. The entire content of the identifiedprior-filed application is hereby incorporated by reference as if fullyset forth herein.

FIELD

The present invention relates to systems and methods for fabricating andcuring large composite structures, and more particularly, embodimentsconcerns a system and method for fabricating and curing large compositeaircraft, aerospace, or other vehicle fuselages, bodies, or other partstructures.

BACKGROUND

The fabrication and curing of large composite structures, such asaircraft fuselages, is a complex process involving tools whichphysically support the composite materials until the composite materialsare at least partially cured. One solution is to fabricate and cure aplurality of independent part segments on different supportive tools,and then assemble the part segments to form the structure. However, thismethod suffers from several problems and limitations, including that theindependent fabrication of the parts requires either that the parts befabricated and cured one at a time, which is inefficient, or thatmultiple fabrication machines be provided and maintained, which iscostly.

Another solution is to fabricate such a structure as a single piece on alarge tool and then disassemble and remove the tool from within thefabricated and cured structure. However, this method also suffers fromseveral problems and limitations, including that the tool must bedesigned to be disassembled into sufficiently small subcomponents so asto be removable through whatever opening remains in the fabricated andcured structure. Further, the processes of assembling and disassemblingso many small tool subcomponents is time-consuming and inefficient.

This background discussion is intended to provide information related tothe present invention which is not necessarily prior art.

SUMMARY

Embodiments address the above-described problems and limitations in theprior art by providing a system and method for fabricating and curinglarge composite aircraft, aerospace, or other vehicle fuselages, bodies,or other part structures, wherein the composite part is at leastpartially fabricated and cured on a tool, cut or otherwise segmented tofacilitate removing it from the tool, removed from the tool withoutdisassembling the tool, and then reassembled off the tool to reform thelarge composite part.

In a first embodiment, a system is provided for fabricating and curing alarge composite part. The system may include a tool, an automated fiberplacement machine, a curing mechanism, a cured material cuttingmechanism, and a reassembly mechanism. The tool may be configured tosupport the large composite structure during the fabrication and curingprocesses, and may include a substructure and one or more mandrelsegments removably attached to the substructure and providing a surfaceon which the large composite part may be fabricated. The automated fiberplacement machine may be configured to apply composite materialcomprising resin and synthetic fibers onto the mandrel segments tofabricate the large composite part as a single piece on the tool. Thecuring mechanism may be configured to cure the composite material on themandrel segments to cure the large composite part on the tool. The curedmaterial cutting mechanism may be configured to cut the large compositepart on the tool into a plurality of trimmed part segments which maythen be removed from the tool without disassembling the tool. Thereassembly mechanism may be configured to join the plurality of trimmedpart segments to reassemble the large composite part off the tool.

In various implementations, the first embodiment may include any one ormore of the following additional features. The tool may include aplurality of the mandrel segments, and the system may further include anuncured material cutting mechanism configured to cut the large compositepart on the tool into a plurality of untrimmed part segments prior tothe curing process. The large composite structure may be an aircraftfuselage which has a length of at least five meters. The substructuremay be constructed of a first material having a first coefficient ofthermal expansion and the mandrel segments may be constructed of asecond material having a second coefficient of thermal expansion whichis lower than the first coefficient of thermal expansion, and themandrel segments may be fixedly attached to the substructure at at leastone location and movably attached to the substructure at at least oneother location. The mandrel segments may include structure featuresconfigured to create corresponding structure components in the largecomposite part. The mandrel segments may include grooves configured toaccommodate the cutting mechanism when cutting the large composite partinto the trimmed part segments. The mandrel segments may include joiningfeatures configured to create corresponding joining components in thetrimmed part segments which facilitate joining the trimmed part segmentsto reassemble the large composite part. The curing mechanism may includean autoclave, the cured material cutting mechanism may include a cuttingdisc, and the reassembly mechanism may include a fastener gun. Thesystem may further include a center hub extending through a longitudinalaxis of the substructure, a first interface element coupled with a firstend of the center hub and a second interface element coupled with asecond end of the center hub, and a rotation mechanism coupled with theinterface elements and configured to allow the tool to be rotated aboutthe longitudinal axis. The system may further include one or more caulplates configured to be secured over the composite material on themandrel segments prior to curing the composite material.

In a second embodiment, a method is provided for fabricating and curinga large composite part. The method may include the following steps. Thelarge composite structure may be supported with a tool during thefabrication and curing processes, and the tool may include asubstructure and one or more mandrel segments removably attached to thesubstructure and providing a surface on which the large composite partmay be fabricated. A composite material comprising resin and syntheticfibers may be applied onto the mandrel segments with an automated fiberplacement machine to fabricate the large composite part as a singlepiece on the tool. The composite material may be cured on the mandrelsegments with a curing mechanism to cure the large composite part on thetool. The large composite part may be cut on the tool with a curedmaterial cutting mechanism into a plurality of trimmed part segmentswhich may then be removed from the tool without disassembling the tool.The plurality of trimmed part segments may be reassembled with areassembly mechanism to reassemble the large composite part off thetool.

In various implementations, the second embodiment may include any one ormore of the following features. The tool may include a plurality of themandrel segments, and the method may further include cutting with anuncured material cutting mechanism the large composite part on the toolinto a plurality of untrimmed part segments prior to the curing process.The large composite structure may be an aircraft fuselage which has alength of at least five meters. The substructure may be constructed of afirst material having a first coefficient of thermal expansion and themandrel segments may be constructed of a second material having a secondcoefficient of thermal expansion which is lower than the firstcoefficient of thermal expansion, and the mandrel segments may befixedly attached to the substructure at at least one location andmovably attached to the substructure at at least one other location. Themandrel segments may include structure features configured to createcorresponding structure components in the large composite part. Themandrel segments may include grooves configured to accommodate the curedmaterial cutting mechanism when cutting the large composite part intothe trimmed part segments. The mandrel segments may include joiningfeatures configured to create corresponding joining components in theplurality of trimmed part segments which facilitate joining the trimmedpart segments to reassemble the large composite part. The curingmechanism may include an autoclave, the cured material cutting mechanismmay include a cutting disc, and the reassembly mechanism may include afastener gun. The method may further include a center hub extendingthrough a longitudinal axis of the substructure, a first interfaceelement coupled with a first end of the center hub and a secondinterface element coupled with a second end of the center hub, and arotation mechanism coupled with the interface elements and configured toallow the tool to be rotated about the longitudinal axis. The method mayfurther include securing one or more caul plates over the compositematerial on the mandrel segments prior to curing the composite material.

This summary is not intended to identify essential features of thepresent invention, and is not intended to be used to limit the scope ofthe claims. These and other aspects of the present invention aredescribed below in greater detail.

DRAWINGS

Embodiments of the present invention are described in detail below withreference to the attached drawing figures, wherein:

FIG. 1 is a depiction of an embodiment of a system engaged in a processof at least partially fabricating and curing a large compositestructure;

FIG. 2 is an exploded perspective view of certain components of thesystem of FIG. 1;

FIG. 3 is an exploded perspective view of certain components of a toolcomponent of the system of FIG. 1;

FIG. 4 is a perspective view of the tool component mounted on rotatingsupport mechanisms and guided vehicle components of the system of FIG.1;

FIG. 5 is a fragmentary perspective view of the rotating supportcomponents rotating and/or lifting the tool component;

FIG. 6 is an exploded perspective view of caul plate components of thesystem of FIG. 1;

FIG. 7 is an exploded perspective view of a mandrel segment and caulplate handling mechanism component of the system of FIG. 1;

FIG. 8 is an exploded perspective view of a part segment handlingmechanism component of the system of FIG. 1;

FIG. 9 is a perspective view of the tool component being assembled;

FIG. 10 is a perspective view of the tool component being transported toan automated fiber placement machine component of the system of FIG. 1;

FIG. 11 is a perspective view of the tool component mounted on theautomated fiber placement machine component for fabrication of the part;

FIG. 12 is a perspective view of the caul plate component being securedover the part prior to curing;

FIG. 13 is a perspective view of a part segment being removed from thetool component following curing and cutting of the part;

FIG. 14 is a perspective of the part segment being trimmed and/ordrilled;

FIG. 15 is a perspective view of the part segment undergoing inspectionof an inner mold line;

FIG. 16 is a perspective view of the part segment undergoing inspectionof an outer mold line;

FIG. 17 is a perspective view of the part segment being positioned forreassembly with other part segments to reform the large compositestructure;

FIG. 18 is a flowchart of an embodiment of a method of at leastpartially fabricating and curing a large composite structure;

FIG. 19 is a cutaway isometric view of a mounting system which may beused with the tool component or a version thereof to attach the mandrelsegment to a substructure, wherein portions of a facesheet of themandrel segment are shown cut away to reveal details underneath;

FIG. 20 is a fragmentary exploded isometric view of an attachmentmechanism component of the mounting system;

FIG. 21 is a fragmentary isometric view of the attachment mechanism ofFIG. 20;

FIG. 22 is a fragmentary isometric view of a configuration of openingsin an implementation of a directional type of the attachment mechanismof FIG. 21; and

FIG. 23 is a fragmentary isometric view of a configuration of openingsin an implementation of a non-directional type of the attachmentmechanism of FIG. 21.

The figures are not intended to limit the present invention to thespecific embodiments they depict. The drawings are not necessarily toscale.

DETAILED DESCRIPTION

The following detailed description of embodiments of the inventionreferences the accompanying figures. The embodiments are intended todescribe aspects of the invention in sufficient detail to enable thosewith ordinary skill in the art to practice the invention. Otherembodiments may be utilized and changes may be made without departingfrom the scope of the claims. The following description is, therefore,not limiting. The scope of the present invention is defined only by theappended claims, along with the full scope of equivalents to which suchclaims are entitled.

In this description, references to “one embodiment,” “an embodiment,” or“embodiments” mean that the feature or features referred to are includedin at least one embodiment of the invention. Separate references to “oneembodiment,” “an embodiment,” or “embodiments” in this description donot necessarily refer to the same embodiment and are not mutuallyexclusive unless so stated. Specifically, a feature, component, action,step, etc. described in one embodiment may also be included in otherembodiments, but is not necessarily included. Thus, particularimplementations of the present invention can include a variety ofcombinations and/or integrations of the embodiments described herein.

Embodiments provide a system and method for fabricating large compositeaircraft, aerospace, or other vehicle fuselages, bodies, or other partstructures, wherein the composite part is at least partially fabricatedand cured on a tool, cut or otherwise segmented to facilitate removingit from the tool, removed from the tool without disassembling the tool,and then reassembled off the tool to reform the large composite part. Asused herein, a “large” part shall mean a part which is, in variousimplementations, at least five meters, or at least ten meters, or atleast fifteen meters in at least one dimension. For example, the largecomposite structure may be a generally cylindrical aircraft fuselagewhich is at least five meters in length along a longitudinal axis.

An embodiment of such a system for fabricating a large compositeaircraft, aerospace, or other vehicle fuselage, body, or other part mayinclude a tool having a substructure and one or more mandrel segmentsremovably attachable to the substructure. The substructure may beconfigured to physically and operationally support the mandrel segmentsduring fabrication and curing of the part. The substructure may havesubstantially any suitable design and shape as may be desired orrequired for a particular application. In one implementation, in whichthe part to be fabricated is a generally cylindrical aircraft fuselage,the substructure may be generally cylindrically shaped, while in otherimplementations, the substructure may be, for example, geometrically orirregularly shaped. The substructure may be constructed of substantiallyany suitable material, such as metal or composite. In oneimplementation, the substructure may include a hub extending along alongitudinal axis C through the substructure, and first and secondinterface elements coupled with opposite ends of the hub and configuredto allow for mounting the substructure on rotatable or fixed and/ormovable structures to facilitate the fabrication, curing, and/or removalof the part.

The mandrel segments may be configured to physical and operationallysupport the part during fabrication and curing of the part. The mandrelsegments may have substantially any suitable design and shape as may bedesired or required for a particular application. The mandrel segmentsmay include structure features configured to create correspondingstructure components in the fabricated part. In one implementation,there may a single mandrel segment, while in other implementations,there may be any number of mandrel segments (e.g., between two and ten,or between two and four) as may be desired or required for a particularapplication. In one implementation, the mandrel segments may besubstantially similar or even identical, while in other implementations,one or more of the mandrel segments may differ significantly in sizeand/or shape from the other mandrel segments. In one implementation, inwhich the part to be fabricated is a generally cylindrical aircraftfuselage, a single mandrel segment may be generally cylindricallyshaped, while multiple mandrel segments may be generally curved so as tofit together on the substructure to form a generally cylindrical shape.

The one or more mandrel segments may be constructed of substantially anysuitable material, such as composite such has bismaleimide or other hightemperature resin and carbon fiber, Kevlar, fiberglass, or othersynthetic fibers. In one implementation, the substructure and themandrel segments may be constructed of the same or relevantly similarmaterials and have significantly the same or the same expansion andcontraction characteristics and/or other relevant characteristics, whilein other implementations, they may be constructed of relevantlydifferent materials and have different expansion and contractioncharacteristics or other relevant characteristics. For example, in oneimplementation, the substructure may be constructed from steel having arelatively high coefficient of thermal expansion, and the mandrelsegments may be constructed from composite or an iron-nickel alloy suchas Invar having a relatively low coefficient of thermal expansion. Insuch a case, the mandrel segments may be fixedly attached to thesubstructure at at least one location and movably attached to thesubstructure at at least one other location with slip joints or othermovable attachment mechanisms to allow the mandrel segments to “float”on the substructure and thereby accommodate differential expansion andcontraction movement or other relative movement of the mandrel segmentsand the substructure (such as while being heated to cure the part).

In one implementation, the mandrel segments may be provided with groovesto accommodate a cutting mechanism to facilitate cutting the part alongdefined lines in order to remove the part from the tool. In variousimplementations, the part may be cut or otherwise segmented intountrimmed segments prior to curing and/or cut or otherwise segmentedinto trimmed segments after curing, while remaining on the tool. In oneimplementation, the resulting part segments may be reassembled off thetool by being butt-joined together, while in other implementations, themandrel segments may be configured to shape the part segments tofacilitate reassembly. For example, the mandrel segments may beconfigured to impart joggle structures or other joining structures tocreate joining components which facilitate joining the part segmentstogether to reform the large composite part.

In one implementation, the system may further include one or more caulplates configured to be positioned on the fabricated part prior tocuring to produce a smoother finish for the cured part.

An embodiment of a method for fabricating the large composite aircraft,aerospace, or other vehicle fuselage, body, or other part may includethe following steps. In one implementation, the method may employ someor all of the components of the above-described system. The tool may beassembled by attaching the one or more mandrel segments to thesubstructure. The part may be at least partially fabricated as a singlepiece on the tool (using, e.g., automated fiber placement technology).If used, the one or more caul plates may be secured (by, e.g., vacuumbagging) over the fabricated part. In one implementation, the part maybe cut or otherwise segmented into untrimmed segment prior to curing.The part may be at least partially cured (by, e.g., autoclaving) on thetool. The at least partially fabricated and cured part may be cut orotherwise segmented into a plurality of trimmed part segments prior toremoval from the tool. The part segments may be removed from the toolwithout disassembling the tool. The part segments may be reassembled toreform the large composite part.

Referring to FIGS. 1-17, an example implementation of theabove-described system 40 is shown adapted for fabricating a largegenerally cylindrical composite fuselage part 42 for an aircraft,wherein the composite fuselage is at least partially fabricated andcured on the tool 44, cut or otherwise segmented to facilitate removingit from the tool 44 without disassembling the tool 44, removed from thetool 44, and then reassembled off the tool 44 to reform the largecomposite fuselage 42. The system 40 may include the tool 44, first andsecond rotation support mechanisms 48, one or more fixed supportmechanisms 50, one or one or more guided vehicles 52, one or moremandrel segment and caul plate handling mechanisms 54, one or more partsegment handling mechanisms 56, an automated fiber placement machine 58,an uncured material cutting mechanism 59; a curing mechanism 60, a curedmaterial cutting mechanism 62, and a reassembly mechanism 64.

The tool 44 may be configured to physically and operationally supportthe part 42 during fabrication and curing. In particular, the tool 44may be moveable and positionable to facilitate fabricating the part 42using the automated fiber placement machine 58, and may be furthermoveable and positionable, with the fabricated part 42 thereon, tofacilitate curing the part 42 using the curing mechanism 60. Referringparticularly to FIG. 3, the tool 44 may include a substructure 68, acentral hub 70 and first and second interface rings 72,74 attached toopposite ends of the hub 70, one or more mandrel segments 76 removablyattachable to the substructure 68, and one or more caul plates 78.

The substructure 68 may be configured to physically and operationallysupport the mandrel segments 76 during fabrication and curing of thepart 42. The substructure 68 may have substantially any suitable designand shape as may be desired or required for a particular application. Inthis example implementation, the part 42 to be fabricated is a generallycylindrical aircraft fuselage, so the substructure 68 may also begenerally cylindrically shaped or, at least, otherwise elongated alongthe longitudinal axis C. The substructure 68 may be constructed ofsubstantially any suitable material, such as metal or composite. In thisexample implementation, the substructure 68 may be constructed of steel.

The central hub 70 may extend through the substructure 68 along thelongitudinal axis C and may be configured to physically and/orfunctionally cooperate with the interface rings 72,74 to facilitatesupporting and/or rotating the substructure 68. In one implementation,the central hub 70 may be configured to experience minimal deflection ofapproximately between 0.055 inches and 0.100 inches when loaded. Thefirst and second interface rings 72,74 may physically and/orfunctionally cooperate with opposite ends of the central hub 70 and maybe configured to facilitate mounting the substructure 68 on the rotatingand/or fixed support mechanisms 48,50 to facilitate fabricating, curing,and/or removing the part 42.

The mandrel segments 76 may be configured to physical and operationallysupport the part 42 during fabrication and curing of the part 42. Themandrel segments 76 may have substantially any suitable design and shapeas may be desired or required for a particular application. In thisexample implementation, the mandrel segments 76 may include surfacefeatures 80 configured to create corresponding components, such asstringers and/or other structural or operational features, in thefabricated part 42.

In one implementation, there may a single mandrel segment 76, while inother implementations, there may be any number of mandrel segments 76(e.g., between two and ten, or between two and four) as may be desiredor required for particular applications. In one implementation, themandrel segments 76 may be substantially similar or even identical,while in other implementations, one or more of the mandrel segments 76may differ significantly in size and/or shape from the other mandrelsegments 76. In this example implementation, there may between two andfour, mandrel segments 76, which are substantially similar in sizeand/or shape to each other, and which and are generally curved so that,when they are attached to the substructure 68, they fit together to formthe generally cylindrical shape of the fuselage part 42.

The one or more mandrel segments 76 may be constructed of substantiallyany suitable material, such as a composite. In one implementation, themandrel segment composite may include bismaleimide or other hightemperature resin and carbon fiber, Kevlar, fiberglass, or othersynthetic fibers. In one implementation, the substructure 68 and themandrel segments 76 may be constructed of the same or relevantly similarmaterials and have the significantly the same or the same expansion andcontraction characteristics and/or other relevant characteristics, whilein other implementations, they may be constructed of relevantlydifferent materials and have different expansion and contractioncharacteristics (i.e., different coefficients of thermal expansion) orother relevant characteristics. In this example implementation, eachmandrel segment 76 may include a Pan board substructure and abismaleimide composite surface.

In one implementation, the substructure 68 and the mandrel segments 76may be constructed of the same or relevantly similar materials and havethe significantly the same or the same expansion and contractioncharacteristics and/or other relevant characteristics, while in otherimplementations, they may be constructed of relevantly differentmaterials and have different expansion and contraction characteristicsor other relevant characteristics. In this example implementation, thesubstructure 68 is constructed from steel having a relatively highcoefficient of thermal expansion, and the mandrel segments 76 areconstructed from bismaleimide and graphite composite having a relativelylow coefficient of thermal expansion. Thus, the mandrel segments 76 maybe fixedly attached to the substructure 68 at at least one location andmovably attached to the substructure 68 at at least one other locationwith slip joints or other movable attachment mechanisms 82 to allow themandrel segments 76 to “float” on the substructure 68 and therebyaccommodate differential expansion and contraction movement or otherrelative movement of the mandrel segments 76 and the substructure 68(such as might occur during curing).

Referring also to FIGS. 19-23, an embodiment of a mounting system 281 isshown configured to removably mount the mandrel segment 276 onto thesubstructure 268. The mandrel segment 276 and the substructure 268 arephysically distinct components which temporarily combine to facilitatesteps in the process of fabricating and curing a large compositestructure. As discussed, the material of the mandrel segment 276 mayhave a different coefficient of thermal expansion than the material ofthe substructure 268. The mounting system 281 may include two or moreattachment mechanisms 282 which allow the mandrel segment 276 to “float”on the substructure 268 and thereby accommodate movement due todifferential expansion and contraction (such as might occur duringcuring) or other relative movement of the mandrel segment 276 and thesubstructure 268.

Referring particularly to FIGS. 20 and 21, each attachment mechanism 282may broadly include a first opening 288 in the substructure 268 or in aplate or other piece welded, coupled, or otherwise physically associatedor associatable with the substructure 268, a second opening 290 in themandrel segment 276 or in a plate or other piece coupled or otherwisephysically associated or associatable with the mandrel segment 276, anda bolt 292 extending through the first and second openings 288,290 andconfigured to secure the mandrel segment 276 to the substructure 268.

At least one of the attachment mechanisms 282A may be of a fixed typewhich provides a fixed point at which the mandrel segment 276 and thesubstructure 268 do not move relative to each other. For this fixed typeof the attachment mechanism 282A, the first and second openings 288,290may be approximately identical in size.

At least one of the attachment mechanisms 282B may be of a directionaltype which allows relative movement along a line in a direction (e.g.,along an X or Y axis) between the mandrel segment 276 and thesubstructure 268. As shown in FIG. 22, for this directional type of theattachment mechanism 268B, at least one of the first and second openings288,290 may be elongated along the line in the direction. In oneimplementation, the mounting system 281 may include a plurality of thedirectional type attachment mechanisms 282B, wherein some may allowrelative movement in a first direction (e.g., along the X axis) and somemay allow relative movement in a second direction (e.g., along a Yaxis).

At least one of the attachment mechanisms 282C may be of anon-directional type which allows relative movement on a plane in anydirection between the mandrel segment 276 and the substructure 268. Asshown in FIG. 23, for this non-directional type of the attachmentmechanism 282C, at least one of the first and second openings 288,290may be oversized. In one implementation, the mounting system 281 mayinclude a plurality of the non-directional type attachment mechanisms282C.

In various implementations, the mounting system 281 may include at leastone fixed type attachment mechanism 282A and at least onenon-directional type attachment mechanism 282C; at least one fixed, atleast one directional, and at least one non-directional type attachmentmechanisms 282A,282B,282C; or at least one fixed type attachmentmechanism 282A, at least two directional type attachment mechanisms 282Boriented in different directions, and at least two nondirectional typeattachment mechanisms 282C. In one implementation, the directional andnon-directional attachment mechanisms 282B,282C may be oriented suchthat the allowed relative movements are all co-planar.

In one implementation, each attachment mechanism 282 may include a firstsurface 294 welded to or otherwise physically associated with thesubstructure 268, wherein the first opening 288 extends through thefirst surface 294; a second surface 296 attachable to or otherwisephysically associatable with the mandrel segment 276, wherein the secondopening 290 extends through the second surface 296; and a bushing 298and a washer 300 which fit over the bolt 292. The first and secondsurfaces 294,296 may be plates made of steel or other metal. The bushing298 may include a sleeve 302 and a flange 304, and may be configured tofit over the bolt 292 such that the sleeve 302 extends into the firstand second openings 288,290 while the flange 304 remains above thesecond surface 296. The washer 300 may be configured to fit over thebolt 292 between the second surface 296 and the flange 304 of thebushing 298. In one implementation, the washer 300 may be constructed ofa metal or other material which is dissimilar to the metal or othermaterial of the second surface 296 so as to minimize galling and bindingwhen the washer 300 moves against the second surface 296. In oneimplementation, the washer 300 may be configured to maintain a space ofapproximately between three thousandths of an inch and twelvethousandths of an inch, or approximately between five thousandths of aninch and ten thousandths of an inch, between the washer 300 and theflange of the bushing 298 to facilitate the relative movement betweenthe mandrel segment 276 and the substructure 268.

In operation, the second surface 296 may be coupled with (by, e.g.,bolts) or otherwise physically associated with the mandrel segment 276;the first and second surfaces 294,296 may be brought together such thatthe first and second openings 288,290 are aligned; the bolt 292 may beinserted through the first and second openings 288,290 and the washer300 and bushing 298 may be applied over the bolt 292; and the bolt 292may be tightened to secure the mandrel segment 276 to the substructure268 (with, e.g., a nut 306). Thereafter, the directional type ofattachment mechanisms 282B and the non-directional type of attachmentmechanisms 282C may allow the mandrel segment 276 and the substructure268 to move relative to each other due to, e.g., differential thermalexpansion.

In one implementation, the mandrel segments 76 may be provided withgrooves 84 to accommodate the uncured and/or cured material cuttingmechanisms 59,62 to facilitate cutting the part 42 along defined linesin a plurality of part segments 86. In one implementation, the partsegments 86 may reassembled by being butt-joined together. In otherimplementations, the mandrel segments 76 may be configured to shape thepart segments 86 to facilitate reassembly. For example, the mandrelsegments 76 may be configured to impart joggle structures or otherjoining structures to enable lap-splicing and/or otherwise joining thepart segments 86 together to reform the large composite part 42.

Referring particularly to FIG. 6, the one or more caul plates 78 may beconfigured to be positioned over the fabricated part 42 on the mandrelsegments 76 and to provide a smoother finish to the cured part 42. Inthis example implementation, the caul plates 78 may be secured inposition by vacuum bagging. In one implementation, each caul plate 78may be constructed of bismaleimide composite and may have a thickness ofapproximately between one-sixteenth inch and one-half inch, or betweenone-sixteenth inch and one-quarter inch, or one-eighth inch.

Referring particularly to FIGS. 4 and 5, the first and second rotationsupport mechanisms 48 may be configured to engage and cooperate with thefirst and second interface rings 72,74 to allow for rotating the tool 44approximately between one degree and three hundred and sixty degrees, orbetween one degree and one hundred and eighty degrees, duringfabrication, curing, and or removal of the part 42. In oneimplementation, the rotation support mechanisms 48 may be furtherconfigured to engage and cooperate with the first and second interfacerings 72,74 to allow for lifting the tool 44 approximately between oneinch and thirty-six inches, or between one inch and twenty-eight inches,or between one inch and twenty inches. In various implementations, thefirst and second rotation support mechanisms 48 may be separate units ormay be connected together.

The one or more fixed support mechanisms 50 may be configured to receiveand physically support the tool 44 during various processes, includingreceiving and physically supporting the tool 44 and the fabricated part42 thereon during the curing process. In one implementation, the fixedsupport mechanisms 50 may engage and cooperate with the first and secondinterface rings 72,74 to support the tool 44. In one implementation, thefixed support mechanisms 50 may be further configured to engage andcooperate with the first and second interface rings 72,74 to allow forlifting the tool 44 approximately between one inch and thirty-sixinches, or between one inch and twenty-eight inches, or between one inchand twenty inches. In various implementations, the first and secondfixed support mechanisms 50 may be separate units or may be connectedtogether.

The one or more guided vehicles 52 may be configured to be positionedunder or otherwise receive or engage the rotation and/or fixed supportmechanisms 48,50 and facilitate moving the support mechanisms 48,50 andthe tool 44 supported thereon to and from, e.g., the automated fiberplacement machine 58 and/or curing mechanism 60. In one implementation,the guided vehicles 52 may be manually guided, while in anotherimplementation, the guided vehicles 52 may be computer guided.

Referring particularly to FIG. 7, the one or more mandrel segment andcaul plate handling mechanisms 54 may be configured to facilitatelifting and positioning the mandrel segments 76 and attaching themandrel segments 76 to the substructure 68, to facilitate removing themandrel segments 76 from the substructure 68, to facilitate lifting andpositioning the caul plates 78 and securing the caul plates 78 (by,e.g., vacuum bagging) over the fabricated part 42 prior to curing, andto facilitate removing the caul plates 78 following curing. Referringparticularly to FIG. 8, the one or more part segment handling mechanisms56 may be configured to facilitate lifting and removing the partsegments 86 from the tool 44 following fabrication, curing, andsegmentation of the part 42. In various implementations, the partsegment handling mechanisms 56 may include edge wedges and clamps tofacilitate removal and securement of the part segment 86 from themandrel segment 76, headers and clamps configured to facilitate removaland securement of the part segment 86 from the mandrel segment 76, andvacuum cups configured to facilitate securing the part segment 86. Eachof the various handling mechanisms 54,56 may be movably positionable orfixedly positioned above, below, or beside the tool 44, as desired orrequired by a particular application. Each of the handling mechanisms54,56 may employ vacuum or non-vacuum technologies for engaging themandrel segment 76, caul plate 78, and/or part segment 86.

The automated fiber placement machine 58 may be configured to apply acomposite material comprising resin and synthetic fibers onto the one ormore mandrel segments 76 to fabricate the large composite part 42 as asingle piece on the tool 44. The uncured material cutting mechanism 59may be configured to cut or otherwise segment the fabricated singlepiece on the tool 44 into a plurality of untrimmed part segments 85prior to curing. The autoclave or other curing mechanism 60 may beconfigured to cure the composite material on the one or more mandrelsegments 76 to cure the large composite part 42 on the tool 44. Thecured material cutting mechanism 62 may be configured to cut orotherwise segment the fabricated and cured part 42 on the tool 44 intothe plurality of trimmed part segments 86 which may then be removed fromthe tool 44 without disassembling the tool 44. In variousimplementations, the cutting mechanism 62 may include drills, punches,knives, saws, and/or discs. The reassembly mechanism 64 may beconfigured to joining the plurality of trimmed part segments 86 so as toreform the large composite part 42 into a single piece off the tool 44.In one implementation, the reassembly mechanism 64 may include afastener gun and the fasteners may include rivets, interference-fitfasteners, and/or bolts.

Referring to FIGS. 9-18, an example implementation of theabove-described method 140 is shown adapted for fabricating the large,generally cylindrical composite fuselage part 42, wherein the compositefuselage 42 is at least partially fabricated and cured on the tool 44,cut or otherwise segmented into the plurality of part segments 86 tofacilitate removing it from the tool 44 without disassembling the tool44, removed from the tool 44, and then reassembled off the tool 44 toreform the large composite fuselage part 42. In one implementation, themethod 140 may employ some or all of the components of theabove-described example system 40.

The tool 44 may be assembled by attaching the one or more mandrelsegments 76 to the substructure 68, as shown in 142. In oneimplementation, the tool 44 may be mounted on the rotatable or fixedsupport mechanisms 48,50, as shown in 144, and rotated or fixedlysupported as desired or required, as shown in 146 and FIG. 9.

The part 42 may be at least partially fabricated as a single piece onthe tool 44, as shown in 148. In one implementation, the fabricationprocess may include installing and compacting stringer charges to formstringers on the part 42, installing and inflating bladders to form thestringers or other structural components, and installing and compactinginner mold line plies, while rotating the tool 44 as desired or neededfor better access. The guide vehicles 52 may then transport the tool 44to the automated fiber placement machine 58, as shown in FIG. 10. Theautomated fiber placement machine 58 may receive the tool 44, such as byengaging the interface rings 72,74, and the rotatable or fixed supportmechanisms 48,50 and guided vehicles 52 may be removed. The automatedfiber placement machine 58 may wrap the entire tool 44 or may wrap eachmandrel segment 76 individually and apply connecting straps betweenindividual mandrel segments 76, as shown in 150 and FIG. 11. Whenfabrication is complete, the tool 44 may then be disengaged from theautomated fiber placement machine 58, remounted on the rotatable orfixed support mechanisms 48,50 and guided vehicles 50, and transportedto the caul plate handling mechanisms 54.

The one or more caul plates 78 may be secured (by, e.g., vacuum bagging)over the fabricated part 42, as shown in 152 and FIG. 12. In oneimplementation, the large composite part may be cut or otherwisesegmented with the uncured material cutting mechanism 59 into theplurality of untrimmed part segments 85 prior to the curing process, asshown in 153. In one implementation, the tool 44, with the caul platesinstalled 78, may be transported to the curing mechanism 60 for curing.The fabricated part 42 may be at least partially cured by the curingmechanism 60 on the tool 44, as shown in 154. In one implementation,following curing, the tool 44 may be moved to the caul plate handlingmechanism 54 and the caul plates 78 may be removed.

The at least partially fabricated and cured part 42 may be cut orotherwise segmented by the cutting mechanism 62 into the plurality oftrimmed part segments 86 prior to removal from the tool 44, as shown in156. The trimmed part segments 86 may be removed from the tool 44 by thepart segment handling mechanism 56 without disassembling the tool 44, asshown in 158 and FIG. 13. In one implementation, the part segments 86may be further trimmed and/or drilled prior to removal from the tool 44.The part segments 86 may be reassembled off the tool 44 to reform thesingle piece large composite fuselage 42, as shown in 160 and FIG. 17.In one implementation, this may include further trimming and/or drillingand/or non-destructive inspection of the part segments 86 prior to,during, and or after reassembly, as shown in 162 and FIGS. 14-16.Non-destructive inspection may be performed for, e.g., inner mold line,outer mold lines, and/or stringers or other structural components.

Although the invention has been described with reference to the one ormore embodiments illustrated in the figures, it is understood thatequivalents may be employed and substitutions made herein withoutdeparting from the scope of the invention as recited in the claims.

Having thus described one or more embodiments of the invention, what isclaimed as new and desired to be protected by Letters Patent includesthe following:

The invention claimed is:
 1. A tool for supporting a large composite part during a fabrication process and a curing process, the tool comprising: a substructure and a mandrel segment removably attached to the substructure and providing a surface on which the large composite part is fabricated and cured, wherein the substructure is constructed of a first material having a first coefficient of thermal expansion and the mandrel segment is constructed of a second material having a second coefficient of thermal expansion which is different from the first coefficient of thermal expansion; a first attachment mechanism attaching the mandrel segment to the substructure at a first location and not allowing relative movement between the mandrel segment and the substructure at the first location; and a second attachment mechanism attaching the mandrel segment to the substructure at a second location and allowing relative movement in at least one direction due to differential thermal expansion between the mandrel segment and the substructure at the second location.
 2. The tool of claim 1, wherein the large composite part has a length of at least five meters and is part of an aircraft fuselage.
 3. The tool of claim 1, the second attachment mechanism comprising an elongated opening which is oriented along a line in a first direction and which allows the relative movement along the line in the first direction due to the differential thermal expansion between the mandrel segment and the substructure at the second location.
 4. The tool of claim 1, the second attachment mechanism comprising an oversized opening which allows the relative movement on a plane in any direction due to the differential thermal expansion between the mandrel segment and the substructure at the second location.
 5. The tool of claim 1, the second attachment mechanism comprising an elongated opening which is oriented along a line in a first direction and which allows the relative movement along the line in the first direction, and the tool further comprising a third attachment mechanism attaching the mandrel segment to the substructure at a third location and comprising an oversized opening which allows the relative movement on a plane in any direction due to the differential thermal expansion between the mandrel segment and the substructure at the third location.
 6. The tool of claim 1, further comprising: a center hub extending through a longitudinal axis of the substructure; a first interface element coupled with a first end of the center hub and a second interface element coupled with a second end of the center hub; and a rotation mechanism coupled with the first and second interface elements and allowing the tool to be rotated about the longitudinal axis.
 7. A tool for supporting a large composite part during a fabrication process and a curing process, the tool comprising: a substructure and a mandrel segment removably attached to the substructure and providing a surface on which the large composite part is fabricated and cured, wherein the substructure is constructed of a first material having a first coefficient of thermal expansion and the mandrel segment is constructed of a second material having a second coefficient of thermal expansion which is lower than the first coefficient of thermal expansion; and a plurality of attachment mechanisms attaching the mandrel segment to the substructure, each attachment mechanism comprising a first opening associated with the substructure, a second opening associated with the mandrel segment, and a bolt extending through the first and second openings and removably securing the mandrel segment to the substructure, the plurality of attachment mechanisms comprising: a first attachment mechanism attaching the mandrel segment to the substructure at a first location, wherein the first and second openings of the first attachment mechanism are a same size and a same shape such that the first attachment mechanism does not allow relative movement between the mandrel segment and the substructure at the first location, and a second attachment mechanism attaching the mandrel segment to the substructure at a second location and allowing relative movement in at least one direction due to differential thermal expansion between the mandrel segment and the substructure at the second location.
 8. The tool of claim 7, wherein at least one of the first and second openings of the second attachment mechanism is elongated along a line in a first direction such that the second attachment mechanism allows the relative movement along the line in the first direction.
 9. The tool of claim 7, wherein at least one of the first and second openings of the second attachment mechanism is larger than the other such that the second attachment mechanism allows the relative movement on a plane in any direction.
 10. The tool of claim 7, the plurality of attachment mechanisms further comprising a third attachment mechanism attaching the mandrel segment to the substructure at a third location and allowing relative movement along a line in at least one direction due to differential thermal expansion between the mandrel segment and the substructure at the third location.
 11. The tool of claim 10, wherein at least the second and third attachment mechanisms are oriented such that the relative movements at the second and third locations are co-planar.
 12. The tool of claim 7, each attachment mechanism further comprising: a first surface physically associated with the substructure, wherein the first opening extends through the first surface; a second surface physically associated with the mandrel segment, wherein the second opening extends through the second surface; and a bushing and a washer fitted over the bolt.
 13. The tool of claim 12, the bushing comprising a sleeve and a flange, and the bushing is fitted over the bolt such that the sleeve extends into the first and second openings and the flange remains above the second surface.
 14. The tool of claim 12, wherein the washer is fitted over the bolt and between the second surface and the flange of the bushing, and the washer maintains a space of between three thousandths of an inch and twelve thousandths of an inch between the washer and the flange of the bushing to facilitate the relative movement of the mandrel segment and the sub structure.
 15. The tool of claim 7, further comprising: a center hub extending through a longitudinal axis of the substructure; a first interface element coupled with a first end of the center hub and a second interface element coupled with a second end of the center hub; and a rotation mechanism coupled with the first and second interface elements and allowing the tool to be rotated about the longitudinal axis.
 16. A tool for supporting a large composite part during a fabrication process and a curing process, the tool comprising: a substructure and a mandrel segment removably attached to the substructure and providing a surface on which the large composite part is fabricated and cured, wherein the substructure is constructed of a first material having a first coefficient of thermal expansion and the mandrel segment is constructed of a second material having a second coefficient of thermal expansion which is lower than the first coefficient of thermal expansion; and a plurality of attachment mechanisms attaching the mandrel segment to the substructure, with each attachment mechanism comprising a first opening associated with the substructure, a second opening associated with the mandrel segment, and a bolt extending through the first and second openings and removably securing the mandrel segment to the substructure, the plurality of attachment mechanisms comprising: a first attachment mechanism attaching the mandrel segment to the substructure at a first location, wherein the first and second openings of the first attachment mechanism are a same size and a same shape such that the first attachment mechanism does not allow relative movement between the mandrel segment and the substructure at the first location, a second attachment mechanism attaching the mandrel segment to the substructure at a second location and allowing relative movement along a line in a particular direction due to differential thermal expansion between the mandrel segment and the substructure at the second location, and a third attachment mechanism attaching the mandrel segment to the substructure at a third location and allowing relative movement on a plane in any direction due to differential thermal expansion between the mandrel segment and the substructure at the third location, wherein at least the second and third attachment mechanisms are oriented such that the relative movements at the second and third locations are co-planar.
 17. The tool of claim 16, wherein at least one of the first and second openings of the second attachment mechanism is elongated along the line in the particular direction such that the second attachment mechanism allows the relative movement along the line in the particular direction.
 18. The tool of claim 16, wherein at least one of the first and second openings of the third attachment mechanism is larger than the other such that the third attachment mechanism allows the relative movement on the plane in any direction.
 19. The tool of claim 16, each attachment mechanism further comprising: a first surface physically associated with the substructure, wherein the first opening extends through the first surface; a second surface physically associated with the mandrel segment, wherein the second opening extends through the second surface; a bushing fitted over the bolt, the bushing comprising a sleeve and a flange and fitted over the bolt such that the sleeve extends into the first and second openings and the flange remains above the second surface; and a washer fitted over the bolt and between the second surface and the flange of the bushing, the washer maintaining a space of between three thousandths of an inch and twelve thousandths of an inch between the washer and the flange of the bushing to facilitate the relative movement of the mandrel segment and the substructure.
 20. The tool of claim 16, further comprising: a center hub extending through a longitudinal axis of the substructure; a first interface element coupled with a first end of the center hub and a second interface element coupled with a second end of the center hub; and a rotation mechanism coupled with the first and second interface elements and allowing the tool to be rotated about the longitudinal axis. 